The present invention relates to a color conversion apparatus for image data and a color conversion method for image data used to color-convert an image when video signals are synthesized by a switcher.
In the process for editing a video signal, a video signal supplied from a camera or the like is supplied to a color conversion circuit. The color conversion circuit color-converts video signals.
Video signals color-converted by the color conversion circuit are supplied to a switcher. A video output signal synthesized by the switcher is supplied to a recording VTR and thereby recorded on a video tape, thus to obtain a video tape on which a color-converted video signal is recorded.
The switcher synthesizes the color-converted video signal with a video signal by a proper method such as wipe or mix. The wipe is to insert other image into a certain image while wiping a certain image with a specific pattern or excluding a certain image from the picture screen. The mix is to fade-in other image while fading-out a certain image. The video signal synthesized by the switcher is supplied to a recording VTR not shown.
The aforementioned color conversion circuit is roughly classified as two color conversion circuits. One color conversion circuit is a first color conversion circuit for color-converting the whole areas of an inputted video signal in the same manner. This color conversion applies to the case that an inputted video signal is corrected so as to become reddish on the whole. The other color conversion circuit is a second color conversion circuit for designating a specific color in an inputted video signal and color-converting such specific color. This color conversion applies to the case that a color of a reddish (specific color) area in the inputted video signal is corrected so as to become a red color with high saturation.
In order to implement such two color conversions, it is proposed to connect the second color conversion circuit to the rear stage of the first color conversion circuit. In this case, an output signal color-converted by the first color conversion circuit is a signal which results from color-converting the inputted video signal. However, since the output signal from the first color conversion circuit is already color-converted, when a specific color is designated by the second color conversion circuit, such specific color cannot be designated precisely. In other words, the second color conversion circuit cannot designate a specific color precisely due to an influence of an outputted result of the first color conversion circuit.
This will hereinafter be described with reference to the aforesaid example. The output signal from the first color conversion circuit is a signal which is reddish on the whole relative to the inputted video signal. If the second conversion circuit with the reddish signal inserted thereto designated a reddish color which becomes a specific color, an area that should not be designated would be designated.
In order to further facilitate the understanding, the following special example will be considered. The first color conversion circuit, for example, color-converts an inputted video signal such that a color component is eliminated from the inputted video signal and the inputted video signal becomes a black and white video signal. Then, the video signal inputted to the second color conversion circuit of the succeeding stage does not contain a color component so that the second color conversion circuit cannot designate a specific color. That is, the second color conversion circuit cannot perform a color conversion.
As described above, when the apparatus includes the first color conversion circuit for color-converting the whole of the inputted video signal and the second color conversion circuit for color-converting the inputted video signal to a specific color, if the second color conversion circuit is connected to the rear stage of the first color conversion circuit, then the succeeding second color conversion circuit cannot perform the accurate color conversion.
It is an object of the present invention to provide a color conversion apparatus in which the succeeding second color conversion circuit can accurately color-convert image data outputted from the preceding first color conversion circuit without being affected by the color-conversion of the first color conversion circuit.
A color conversion apparatus for image data according to the first invention is a color conversion apparatus for image data for color-correcting or color-converting image data, and includes a first color-converting means for effecting a first color-conversion on inputted image data, a second color-converting means for effecting a second color-conversion by adding a correction signal, which is corrected so as to cancel the first color-conversion carried out by the first color converting means out, to a specific area of image data outputted from the first color converting means and a key signal generating means for generating a key signal from the image data supplied to the first color converting means.
According to the first invention, the first color-conversion is effected on the image data by the first color-converting means, the second color-converting means effects the second color conversion by adding the correction signal, which is corrected so as to cancel the first color conversion carried out by the first color-converting means out, to the specific area of the image data outputted from the first color-converting means and the key signal generating means generates the key signal from the image data supplied to the first color-converting means, the outputted result of the succeeding color converting means for color-converting the specific color can be prevented from being affected by the outputted result of the preceding color-converting means for color-converting the whole of the image.
In a color conversion apparatus for image data according to the second invention, the second color-converting means uses the correction signal which is corrected so as to cancel the first color-conversion for image data carried out by the first color-converting means, whereby color conversion can be prevented from being affected by color conversion of image data carried out by the first color-converting means.
According to the second invention, since the second color-converting means uses the correction signal which is corrected so as to cancel the first color conversion for image data carried out by the first color-converting means out, color conversion can be prevented from being affected by the color conversion for image data carried out by the first color converting means. Therefore, the whole of image can be color-converted and the specific color can be color-converted at the same time, and can be prevented from affecting each other.
In a color conversion apparatus for image data according to the third invention, a key signal generating means includes a color coordinate rotation means for designating a color coordinate direction in which a key signal is generated.
According to the third invention, since the key signal generating means includes the color coordinate rotation means for designating the color coordinate direction in which the key signal is generated, a coordinate axis expressing a color space can be rotated in accordance with a color direction in which the key signal is generated.
A color conversion method of image data according to the fourth invention is a color conversion method of image data for color-correcting or color-converting image data, and comprises the steps of effecting a first color-conversion on inputted image data, generating a key signal from image data outputted by the first color-conversion, and effecting a second color-conversion by adding a correction signal, which is corrected so as to cancel the first color-conversion carried out by the first color-converting means out, to a specific area of image data color-converted by the first color-conversion, thereby color-converting only the area of specific color.
According to the present invention, a result which is obtained by color-converting a specific color at the succeeding stage can be prevented from being affected by a result which is obtained by color-converting the whole image at the preceding stage.
In a color conversion method of image data according to the fifth invention, the key signal is multiplied with image data indicative of a color area which results from subtracting conversion image data from image data of specific color.
According to the fifth invention, the image data indicative of the color area in which the conversion image data is subtracted from the image data of specific color is generated, whereby the correction signal can be easily generated.
In a color conversion method of image data according to the sixth invention, the first color-conversion data for color-converting the whole image of image data and image data of specific color are entered by an input means.
According to the sixth invention, image data that is used to generate the correction signal can easily be generated y entering image data of specific color.
A color conversion apparatus of image data according to the seventh invention is a color conversion apparatus of image data for color-converting inputted image data, and includes a parameter input means for inputting a first color-conversion parameter, a second color-conversion parameter and a color-designating parameter, a first color-converting means for effecting a first color-conversion on the inputted image data, a key signal generating means for generating a key signal indicative of an area having a color designated by the color-designating parameter of the inputted image data, a second color-converting means for effecting a second color-conversion on outputted image data outputted from the first color-converting means at its area indicated by the key signal, and a control means for supplying a first control signal to the first color-converting means such that the first color-conversion becomes a color-conversion corresponding to the first color-conversion parameter and supplying a second control signal to the second color conversion circuit such that the second color-conversion becomes a color-conversion in which the first color-conversion is canceled from the color-conversion corresponding to the second color-conversion parameter.
Furthermore, according to the seventh invention, since the first color-conversion parameter, the second color-conversion parameter and the color-designating parameter are entered to control the color-conversion, a result which is obtained by the succeeding color-conversion of a specific color can be prevented from being affected by a result which is obtained by the preceding color-conversion of the whole of the image by designating a desired color. This is also true in the eighth invention to the twelfth invention.